Manufacturing generally involves many operations including, but not limited to the formation of indentations, depressions, ways, slots, punching, bores, and holes. For the sake of discussion reference to all of these will be by the use of the word(s) hole, holes, etc. or something similar.
A common situation in manufacturing is the measurement of holes. When the holes are very small it may be difficult to measure the parameters of a hole or bore, such as but not limited to, depth, diameter, bevel, edges, roundness, etc. This may present a problem.
Measurement of a hole by direct contact with a measuring instrument may affect the hole (e.g. scratching, gouging, foreign deposits, etc.) or the instrument (e.g. material on the instrument, damage to the instrument, etc.) and not yield good consistent results. This may present a problem.